The purpose of the cultivator, according to the present invention, is to cultivate the soil between the rows, destroying the weeds that grow there without injuring the crops in the rows. Such vegetables as beans, peas, etc. can also be cultivated, and not only in the sprouting stage but even when they have arrived at a certain height.
German OS 1 813 079 discloses a cultivator for crops planted in rows in which chopping tools are mounted on vertical shafts, and the shafts and hence the rotated chopping tools are positioned by parallelogram rods suspended from the machine frame. The chopping tools are disks, on which blades that project downward can be mounted interchangeably. The blades of the resulting chopping tools penetrate into the soil, with the total weight of each tool coming into action along with that of the shaft. The disks of course limit the depth of penetration into the soil. The tools are accordingly not resilient and their depth of penetration cannot be controlled. It is also impossible to precisely cultivate some crops, maize for example, near their roots with tools of this type. The disks entail a risk of nicking or otherwise damaging at least the above-ground sections of the stalks. The roots themselves can become damaged by the stationary blades. A relatively wide strip that cannot be cultivated next to the crops is accordingly necessarily left along the row when chopping tools of this type are employed.
Another cultivator is known from German Patent 2 166 742. A common drive mechanism with a transmission that distributes force to various vertical shafts extends over the operating width inside the frame of the machine. The distance between the individual shafts cannot be varied. To adjust to different distances between rows or to rows of different widths, chopping tools are mounted on only some of the tool holders. The pillow block can be detached from the machine frame and shifted laterally to provide the adjustment. The chopping tools are more or less vertical prongs that travel on more or less cylindrical tracks and must be positioned so that they will not damage the plants in the row. Since crops expand as they grow, the strip of soil that cannot be reached with the prongs to the right and left becomes larger, and the weeds that grow there can also not be taken care of. Another drawback is that the depth of penetration of the individual chopping tools between the rows cannot be established separately, and, when the ground is undulatory, some of the prongs can penetrate too far into the soil and in some circumstances damage the roots of the crops, while the prongs will not even reach to the surface of the soil in other areas.